The specific aims of this proposal are to select high affinity, human, monoclonal antibodies specific for HIV-1 and Hepatitis B virus for expression in the phage display system, pCOMB3, for random mutagenesis and selection of higher affinity binding molecules that neutralize the virus and to re-express selected molecules in the baculovirus system in order to obtain full length antibodies for binding studies. The long- term goal of this project is to develop antibodies that could potentially be used as therapeutic agents and to develop a system whereby new molecules can be selected against viral mutants that may escape therapy. These specific aims will be carried out by cloning the VH and VL gene segments as a single chain Fv fused to cpIII of M13 bacteriophage, PCR- based random mutagenesis of the CDRs and selection against the antigen using phage particles and re-expression in baculovirus and purification and analysis of the selected molecules.